Fixed issue with FastSign() on WebGL/Safari

BenGraterUnity · BenGraterUnity · commit f0119ad2a70b · 2025-06-17T14:56:04.000-07:00
diff --git a/com.unity.postprocessing/PostProcessing/Shaders/Colors.hlsl b/com.unity.postprocessing/PostProcessing/Shaders/Colors.hlsl
@@ -597,7 +597,7 @@ float3 LiftGammaGainHDR(float3 c, float3 lift, float3 invgamma, float3 gain)
 
     // ACEScg will output negative values, as clamping to 0 will lose precious information we'll
     // mirror the gamma function instead
-    return FastSign(c) * pow(abs(c), invgamma);
+    return sign(c) * pow(abs(c), invgamma);
 }
 
 //
diff --git a/com.unity.postprocessing/PostProcessing/Shaders/StdLib.hlsl b/com.unity.postprocessing/PostProcessing/Shaders/StdLib.hlsl
@@ -116,6 +116,7 @@ float4 Max3(float4 a, float4 b, float4 c)
 
 // https://twitter.com/SebAaltonen/status/878250919879639040
 // madd_sat + madd
+// Incorrect result on WebGL/Safari with A17 or M3 processors.
 float FastSign(float x)
 {
     return saturate(x * FLT_MAX + 0.5) * 2.0 - 1.0;

Original file line number	Diff line number	Diff line change
`@@ -597,7 +597,7 @@ float3 LiftGammaGainHDR(float3 c, float3 lift, float3 invgamma, float3 gain)`
`597`	`597`
`598`	`598`	`// ACEScg will output negative values, as clamping to 0 will lose precious information we'll`
`599`	`599`	`// mirror the gamma function instead`
`600`		`- return FastSign(c) * pow(abs(c), invgamma);`
	`600`	`+ return sign(c) * pow(abs(c), invgamma);`
`601`	`601`	`}`
`602`	`602`
`603`	`603`	`//`
Original file line number	Diff line number	Diff line change
`@@ -116,6 +116,7 @@ float4 Max3(float4 a, float4 b, float4 c)`
`116`	`116`
`117`	`117`	`// https://twitter.com/SebAaltonen/status/878250919879639040`
`118`	`118`	`// madd_sat + madd`
	`119`	`+// Incorrect result on WebGL/Safari with A17 or M3 processors.`
`119`	`120`	`float FastSign(float x)`
`120`	`121`	`{`
`121`	`122`	`return saturate(x * FLT_MAX + 0.5) * 2.0 - 1.0;`